Core B presents an in vitro/murine bone marrow macrophage "screen" to test compounds arising from projects 1 and 3 for evidence of specific activity in inhibiting the in vitro growth of a panel of clinical isolates and laboratory strains of M. tuberculosis. Because it is unlikely that significant numbers of new compounds will become available in the first year, work will begin in the second year. Moreover, formal; arrangements with the industrial partner (SmithKline Beecham; Project 3) have yet to be made. Subsequent testing of promising leads in our whole animals will come under Contract NIH, NIAID N01 AI-45239 ("Animal Model Testing of Anti-TB Drugs"; I.M. Orme, PI).